Electric lamp



C. G. SMITH Sept. 24, 1935.

ELECTRIC LAMP Original Filed July 3, 1929 3 Sheets-Sheet l m 3 m m INVENTOR C. G. SMITH ELECTRIC LAMP Sept. 24, 1935.

Original Filed July 3, 1929 3 Sheets-Sheet 2 FIG. 2

C. G. SMITH ELECTRIC LAMP- Sept. 24, 1935.

Original Filed July 3, 1929 3 Sheets-Sheet 5 INVENTOR 'Ch/gYQLEJ 6. JM/ 7'/-/ Patented Sept. 24, 1935 UNITED STATES ELECTRIC LAMP Charles G. Smith, Medford, Mass, assignor, by

mesne assignments, to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application July 3, 1929, Serial No. 375,635

' Renewed December 30, 1932 I 18 Claims. (Cl. 176-122) This invention relates to electrical lamps and especially to the induction type of lamp disclosed in Patent 843,534. In this patent Hewitt discloses an electrodeless lamp in which high frequency currents are used. By making a sealed container having a, quantity of vapor or gas at a reduced pressure, the secondary of a high frequency circuit, it is possible to cause the lamp to emit an intense glow. However, a lamp such as the Hewitt patent discloses can not be operated for any extended length of time at great brilliancy without destroying the lamp. It is of course possible to operate the lamp so that a soft glow is emitted in which case the glass container will become moderately warm. Trouble is experienced when it is desired to operate this lamp at such brilliancy as to-more or less simulate the intensity of an electric are. This invention is an improvement over the above mentioned Hewitt patent.

In general my invention contemplates the. energization of a small portion of a large lamp. This large lamp may take on a variety of shapes and is preferably made of quartz. By changing the portion of the lamp energized and cooling the remaining portions of the lamp, it is possible to obtaina light in which the temperature-and intensity are comparable to that of the electric are. It is evident that a light of this character if comparable in intensity to the electric arc is superior thereto because of the steadiness and ease with which the intensity of such a light may be modulated. Furthermore, the lamp and apparatus are practically indestructible as regards ordinary usage. Y

Lamps of this character maybe used in projection machines of various characters, searchlights and other apparatus where an intense source of light is necessary. Referring to the drawings, Figure 1 shows a preferred embodiment of the invention.-

Figure 2 shows a modified form of the invention.

Figure 3 is a sectional end view of the form shown in Figure 2. r

Referring to Figure 1, l is a quartz tube having rounded ends 2 and 3. This tube is very carefully cleaned and freed of all adsorbed gases and exhausted. During the exhausting the quartz is preferably heated to a high temperature and thereafter the tube is washed out with helium or hydrogen of as great a purity as may be obtained by the well known methods. The tube is then exhausted and the washing ,repeated several times. 1 During the exhausting, the gas within the tube is ionized by a highfrequency coil to cause a light to be emitted. By means of a spectroscope the purity of the gas within the tube maybe visually observed. ,The washings are repeated as many times as may be necessary to obtain a pure 6 spectrum of the-gas used in washing. The tube is then filled. with helium, neon or any other desirable gas. .It is to beunderstood of course that while I prefer to wash the tube out with helium during the exhausting steps, the gas which 10 is ultimately to fill the tube may be used as the washing mediums The pressure of the helium or other gas is preferably between 1 and 5 mm. of

mercury. v

While it is not essential; I preferably dispose a 15 ring of metal 5 within one or both of the ends 2 and 3. Welded to the rings are wires 6 carrying getter capsules 1. These getter capsules are well known in the art and as a rule contain metallic magnesium. 20

The getter material is vaporized byany of the well known methods and in the construction shown will tend to condense upon the inside of the end chambers 2 and 3. Any material going. through the-tube will be promptly vaporized dur- 25 ing the operation thereof and driven to the colder ends.

Surrounding tube I is a coil I0 adapted to be excited by high frequency from an oscillatory circuit ll. While any desirable frequency may 30 be used I have found that a frequency, the wave length of which is about from 5 to 15 meters, is very satisfactory. Tube l is disposed in the manner shown through apertures of a reflectorl5 of any of the well known varieties. A lens I6 35 may be disposed in front of the reflector to operate upon the light beam in any desirable manner. In order to move tube I so that the portion of the 'tube energized will constantly change,

' I preferably dispose means at each end for re- 40 ciprocating the tube. These means are shown as cables or ropes!!! attached to a suitable clamp 2| fitting over the rounded ends of the tube. By constricting the tube at 22 a firm hold thereon may be obtained by the clamps. Suitable 45 mechanism not shown may be used to reciprocate the tube up and down. Preferably the travel of the tube is such that the end portions from constricted portion22 do not come within the zone of infiuence'of coil I0. The speed of travel of the tube is dependent entirely on how much energy is being put into the tube, the dimensions of the tube and temperature of the surrounding medium. Forquartz, it is desirable that the temperature be kept be- 55 peratures have been used.

In order to conserve the light, coil I0 may be made of highly polished silver or copper. Instead of a coil surrrounding the tube, two pancake coils on opposite sides of the tube may be used as shown in the modification in Figures '2 and 3. The coil may also be made of hollow tubing which may be cooled by a circulating liquid.

The modification in Figures 2 and 3 comprises I a toroidal or doughnut shaped quartz tube 30 prepared in substantially the same manner as the tube in Figure 1. This tube may be supported by a spider 32 engaging the inner surface of the tube in various places. As shown in section in Figure 3 this spider may consist of two split portions 33 and 34 adapted to be clamped together and engage the inner curved surface of tube 30. It is evident that any other suitable supporting means may be used if desired.

Tube 30 may be divided into a plurality of separate tubes'by partitions 31, 38 and 39. Each of the tubes thus formed may have individual side arms 3i carrying a getter 'I supported on a 'ring of metal 5. The tubes are exhausted through the side arms which are then sealed off.

In order to energize this tube, two coils 35 and 36 of heavy metal are disposed on opposite sides of a portion of the tube. The diameter of these coils is preferably approximately equal to the projected surface of tube 30. These coils may be of highly polished silver or copper if desired although it is evident that the coil itself will not obstruct very much light. The coils are connected so as to form a continuous coil and is energized by the oscillating circuit II in a manner similar to the structure shown in Figure 1. Reflector 40 and lens It may be provided to concentrate the light produced.

In order to move the tube, the spider is mounted upon a shaft 4i carrying a pulley 42 which may be driven by any suitable means. While air cooling may be relied upon, I preferably have a portion of the tube at all times dipping into a quantity of water 43.

Tubes of this character with very pure gas have been found to give an intense light.

Such lights are highly eflicient and because of the ease by which they may be modulated may be found useful for systems in which electrical impulses are to be transmitted into light impulses such as picture transmitting systems and television systems. In such systems as well .as projection systems for moving pictures the lamp may very easily be modulated so that it is dark rather than cutting off the light by mechanical means. In this way, a tube may be operated at a higher intrinsic brilliancy since it may cool off, for the dark portion of time.

I claim:

1. An induction lamp comprising an exhausted container having a gas at a reduced pressure, means comprising a coil adapted to be excited by high frequency for energizing the lamp and means for changing the portion of the lamp excited.

2. An induction lamp comprising a container of refractory transparent material, a gas at a reduced pressure therein, means comprising a coil adapted to be energized by high frequency for exciting a portion of said lamp and means 3. An induction lamp comprising an exhausted container of a refractory material, a gas at a 2,015,824 low about 500 or 600 C. although higher temreduced pressure therein, means comprising a coil adapted to be energized by high frequency for energizing a portion of the lamp, said coil being so constructed as to reflect light, and means for changing the portion of the lamp excited.

4. An induction lamp comprising an elongated sealed container having a gas at a reduced pressure, a coil adapted to be excited by high frequency to energize a portion of said container, 10 and means for obtaining a relative reciprocating movement between said container and said coil to change the portion excited.

5. An induction lamp comprising an elongated exhausted container having a gas at a reduced 15 pressure therein, a coil adapted to be excited by high frequency for energizing a portion of said lamp, and means cooperating with the ends of said container for reciprocating it with respect to said coil whereby a continuously chang- 20 ing different portion of the lamp is energized at all times.

6. An induction lamp comprising an elongated quartz tube, exhausted and containing gas at a reduced pressure, a coil adapted to be excited by 5 high frequency in proximity to a portion of said tube to energize said portion and means engaging at least one end of said tube for reciprocating it with respect to said coil whereby a continuously changing portion of the tube is ener- 30 gized.

'7. An induction lamp comprising an elongated quartz tube containing gas at a reduced pressure, a coil of highly reflecting metal adapted to be excited by high frequency for energizing 5 a. portion of said tube, and means for reciprocating said tube whereby a continuously changing portion of said tube is energized.

8. An induction lamp comprising an elongated sealed container having a gas at a reduced pres- 40 sure therein, a coil adapted to be excited at high frequency to energize a portion of the said container, and means for obtaining arelative movement betweenthe said container and the said coil to change the portion excited. 45

9. An induction lamp comprising an elongated sealed container having a gas at a reduced pressure therein, a coil adapted to be excited by high frequency for energizing a portion of the lamp, and means for moving the said container 5 with respect to the coil whereby a continuously changing different portion of the lamp is energized at all times.

10. An induction lamp comprising an elongated quartz tube, exhausted and containing gas at 55 a reduced pressure. a coil adapted to be excited by high frequency in proximity to a portion of the said tube to energize the said portion and means for continuously changing the portion of the tube to be energized. 0

11. An induction lamp comprising an elongated quartz tube containing gas at a reduced pressure, a coil of highly reflecting metal adapted to be excited by high frequency for energizing a portion of the said tube and means for a con- 65 tinuously changing portion of the said tube to be energized.

12. An induction lamp comprising an exhausted container having a gas at a reduced pressure, means for energizing a portion of the lamp and 7 means for changing the portion of the lamp excited.

13. An induction lamp comprising an exhausted toroidal container having a gas at a reduced pressure therein, said container being rotatively 7 mounted, means for intensely energizing the lamp, means for rotating the lamp, and means for continuously cooling successive portions of the lamp.

14. An induction lamp comprising an exhaust ed toroidal container having a gas at a reduced pressure therein, and adapted to be continuously rotated, a coil adjacent the container and adapted for the energization thereof, and means for rotating the container, at least a portion of said container remaining within activating distance from the coil during said rotation.

15. An induction lamp comprising an exhausted toroidal container having a gas at a reduced pressure therein, and adapted to be continuously rotated, a coil adjacent each side of the container and adapted for the energization thereof, and means comprising a pulley for rotating the lamp to change the portion of the lamp excited.

16. An induction lamp comprising an exhausted toroidal container having a gas at a reduced pressure therein, a rotatively mounted carrying member for carrying the container, a coil adjacent each side of the container and adapted for the energlzation thereof, and means for rotating the lamp between the coils to change the portion of the lamp excited.

1'7. A gaseous lamp comprising a transparent vessel containing gas at reduced pressure, means for successively inducting visible electric discharges through said gas in different limited portions of said vessel, and means for cooling the induced portions of said tube during the intervals between successive inductions.

18. A gaseous lamp comprising a transparent vessel containing gas at reduced pressure, means for successively inducing in predetermined order visible electric discharges through said gas in different limited portions of said vessel, and means for cooling the induced portions of said tube during the intervals between successive inductions.

CHARLES G. SMITH. 

